Key parameters affecting the initial release (burst) and encapsulation efficiency of peptide-containing poly(lactide-co-glycolide) microparticles

Evaluation of biodegradable polyester-co-lactone microparticles for protein delivery

“…Additionally, the hydrophobicity of the polymer can affect the drug release by reducing the rate of water penetration into the microspheres and drug egress to some extent compared to the less hydrophobic polymers 42 . Furthermore, different particle morphologies may affect the protein release profile through its effect on the microspheres porosity and the distribution of the drug within the matrix 29,43 . The release profiles of either a-CH or LS under sink conditions from different batches are shown in Figures 4 and 5.…”

A reproducible accelerated in vitro release testing method for PLGA microspheres

“…molecular weight, copolymer ratio and crystallinity) (Park, 1995) and the drug (Miyajima et al, 1998), as well as key quality attributes (e.g. particle size, morphology, porosity, and drug loading) of the PLGA microspheres may affect in vitro drug release characteristics (Dunne et al, 2000;Ehtezazi and Washington, 2000;Luan et al, 2006;Panyam et al, 2003). Risperidone, a tertiary amine drug with a pKa of 8.18 (20°C), has been shown to catalyze PLGA hydrolysis and degradation, thus resulting in a dramatic decrease in polymer molecular weight (Fig.…”

Novel carrier system for enhancing oral delivery of metformin

“…In such cases, the initial amount of of drug released can serve as a loading dose and the remaining amounts of drug released slowly over time will serve as the maintenance dose. Drug release from the formulations was sustained for up to 20 h with only 50% of the metformin hydrochloride being released after 16 h. This slow phase of drug release is attributable to gradual drug release from the core of the lipid matrices via diffusion-controlled processes (Luan, 2006).…”